Unable to deploy out-of-the-box Employee Roster starter application war

2019-04-10 17:49:50,932 ERROR [org.jboss.as.controller.management-operation] (Controller Boot Thread) WFLYCTL0013: Operation ("deploy") failed - address: ([("deployment" => "employee-rostering-webapp-7.18.0.Final-redhat-00002.war")]) - failure description: {
    "WFLYCTL0412: Required services that are not installed:" => ["jboss.naming.context.java.\"${org.optaweb.employeerostering.persistence.datasource:java:jboss\".datasources.ExampleDS}"],
    "WFLYCTL0180: Services with missing/unavailable dependencies" => [
        "jboss.persistenceunit.\"employee-rostering-webapp-7.18.0.Final-redhat-00002.war#optaweb-employee-rostering-persistence-unit\".__FIRST_PHASE__ is missing [jboss.naming.context.java.\"${org.optaweb.employeerostering.persistence.datasource:java:jboss\".datasources.ExampleDS}]",
        "jboss.persistenceunit.\"employee-rostering-webapp-7.18.0.Final-redhat-00002.war#optaweb-employee-rostering-persistence-unit\" is missing [jboss.naming.context.java.\"${org.optaweb.employeerostering.persistence.datasource:java:jboss\".datasources.ExampleDS}]"
    ]
}
2019-04-10 17:49:50,938 INFO  [org.jboss.as.server] (ServerService Thread Pool -- 37) WFLYSRV0010: Deployed "employee-rostering-webapp-7.18.0.Final-redhat-00002.war" (runtime-name : "employee-rostering-webapp-7.18.0.Final-redhat-00002.war")
2019-04-10 17:49:50,939 INFO  [org.jboss.as.controller] (Controller Boot Thread) WFLYCTL0183: Service status report
WFLYCTL0184:    New missing/unsatisfied dependencies:
      service jboss.naming.context.java."${org.optaweb.employeerostering.persistence.datasource:java:jboss".datasources.ExampleDS} (missing) dependents: [service jboss.persistenceunit."employee-rostering-webapp-7.18.0.Final-redhat-00002.war#optaweb-employee-rostering-persistence-unit".__FIRST_PHASE__, service jboss.persistenceunit."employee-rostering-webapp-7.18.0.Final-redhat-00002.war#optaweb-employee-rostering-persistence-unit"]